Objective
The project is devoted to the theoretical study of disordered ultra-cold gases. We focus on two problems:
1. BOSE-EINSTEIN CONDENSATION NEAR RESONANT IMPURITIES: by tuning the atom-impurity scattering length near a Feshbach resonance, atoms can be trapped into a bound state localized around the impurity. We first solve (exactly) the problem of two interacting bosons in the presence of the impurity using Green functions. We then write an ansatz for the many-bosons condensate wavefunction and calculate the energy spectrum of elementary excitations. We determine the limiting number of bosons above which the condensate is unstable due to the repulsive boson-boson interaction and estimate the lifetime of the condensate against decay due to inelastic processes. Finally, we consider many impurities randomly distributed on an optical lattice. We derive an effective low-energy lattice Hamiltonian and we investigate the resulting quantum phase diagram numerically.
2. DISORDER EFFECTS IN FERMI SUPERFLUIDS: starting from the Bogoliubov-De Gennes equations of BCS theory, we investigate the local properties of the gas near a single impurity. We calculate the energy spectrum of quasiparticles and the spatial profiles of the atoms density and the gap parameter. We then discuss the effects of a quenched disorder on the condensate fraction and super-fluid density of the gas across the BEC-BCS crossover. We discuss explicitly the most interesting case of tuning the fermion-impurity scattering length near a resonance. The formation of bound states fermion-impurity is detrimental to super-fluidity, as it breaks Cooper pairs. We generalise the Abrikosov and Gorkov theory for superconductors with paramagnetic impurities to this novel system. We calculate energy gap and super-fluid density as a function of impurity concentrations and scattering lengths. Finally we discuss methods to detect the predicted gapless super-fluid phase in trapped Fermi gases.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
- natural sciences physical sciences condensed matter physics quasiparticles
- natural sciences physical sciences optics spectroscopy absorption spectroscopy
- natural sciences physical sciences electromagnetism and electronics superconductivity
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Keywords
Project’s keywords as indicated by the project coordinator. Not to be confused with the EuroSciVoc taxonomy (Fields of science)
Project’s keywords as indicated by the project coordinator. Not to be confused with the EuroSciVoc taxonomy (Fields of science)
Programme(s)
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Topic(s)
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Call for proposal
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
FP6-2005-MOBILITY-5
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Funding Scheme
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Coordinator
ORSAY
France
The total costs incurred by this organisation to participate in the project, including direct and indirect costs. This amount is a subset of the overall project budget.